TOOL TO MAKE AT LEAST A CREASE ON A RELATIVELY RIGID MATERIAL, SUCH AS FOR EXAMPLE CARDBOARD

Document Type and Number:

WIPO Patent Application WO/2010/029416

Kind Code:

A2

Abstract:

Tool (10) to make at least a crease on a sheet or a strip (11) made of at least relatively rigid material. The tool (10) is able to be selectively moved in relation to the sheet or strip (11), in order to define at least a first operative position in which it is able to perform a continuous or blind crease (11a), and a second operative position in which it is able to execute a through or segmented crease (11b), or is able to execute a true and proper cut.

1. Tool to make at least a crease on a sheet or a strip (11) made of at least relatively rigid material, characterized in that it is able to be selectively moved in relation to the sheet or strip (11), in order to define at least a first operative position in which it is located at a first level with respect to the sheet or strip (11), and is able to perform a continuous or blind crease (1 Ia), and a second operative position in which it is located in a second level, which is lower than the first level, with respect to the sheet or strip (11), and is able to execute a through or segmented crease (1 Ib), or is able to execute a cut. 2. Tool as in claim 1, characterized in that it comprises at least a disk (15) made of rigid material provided circumferentially with at least a cutting segment (16), able to execute a through or segmented crease (1 Ib), or a cut, on the thickness of said sheet or strip (11), and at least a crown (17) made of elastically deformable material, normally disposed to cover at least said cutting segment (16) of the disk (15), able to perform a continuous or blind crease (1 Ia).

3. Tool as in claim 1 or 2, characterized in that said crown (17) has a level of hardness such that, at a first working pressure, it resists deformation and executes a continuous or blind crease (1 Ia) on the thickness of said sheet or strip (11), and such that, at a second working pressure, higher than said first working pressure, it is able to deform elastically in a substantially radial direction, toward the inside of said disk (15), so as to uncover said cutting segment (16) and allow to execute the relative through or segmented crease (1 Ib), or cut, on the sheet or strip (11).

4. Tool as in any claim hereinbefore, characterized in that said disk (15) comprises a plurality of cutting segments (16) angularly offset with respect to each other by a determinate angular pitch.

5. Tool as in any claim hereinbefore, characterized in that said crown (17) is disposed to cover at least a lateral flank (16a) and an external circular top (16b) of each cutting segment (16).

6. Tool as in any claim hereinbefore, characterized in that said crown (17) comprises two annular parts (19, 20), each of which is disposed to cover a relative opposite lateral flank (16a) of the cutting segment and, jointly, to cover the external circular top (16b).

7. Tool as in any claim hereinbefore, characterized in that the elastically deformable material of the crown (17) has a level of hardness comprised between about 45 and about 65 units of the Shore scale.

8. Tool as in any claim hereinbefore, characterized in that it comprises a rotary body (12) on which at least two disks (15) are mounted, substantially parallel and coaxial with respect to each other, to simultaneously execute at least two parallel creases (1 Ia5 1 Ib), or cuts, on the sheet or strip (11).

9. Tool as in claim 8, characterized in that it comprises a spacer element (21) interposed between said two disks (15) and able to keep them distanced from each other by a determinate pitch. 10. Tool as in claim 8 or 9, characterized in that at least one of said two disks (15) is associated laterally with a metal edge (22) that extends radially from the rotary body (12).

Description:

"TOOL TO MAKE AT LEAST A CREASE ON A RELATIVELY RIGID MATERIAL, SUCH AS FOR EXAMPLE CARDBOARD" ψ * H: H= *

FIELD OF THE INVENTION The present invention concerns a tool used to make at least a crease on a sheet, or a strip, made of a relatively rigid material, such as cardboard, plastic or materials having a similar characteristics of rigidity. In particular, with the present invention it is possible to make, using the same tool, both a blind or continuous crease, and also a through crease or in segments. Here and in the following description by blind crease we mean a shaping made with a deformation through compression of the thickness of the material, while by through crease we mean a shaping in which at least a cut segment is provided through the thickness.

BACKGROUND OF THE INVENTION In the packing or packaging sector, plants are known which are used to carry out a plurality of processes, cuts and/or creases, or segments of preferential folding, on a packing material, for example cardboard, so as to facilitate and guide the folding of the sheet, to define a box for packaging.

In general, such plants are suitable to receive a continuous strip of such material and are provided with processing units able to carry out, on the strip, transverse and longitudinal creases distanced with respect to each other by a determinate pitch.

The processing units can also be suitable to perform the cutting to size of the strip, to define single sheets. The sheets are made in a size to correspond to the size of box to be made.

Two types of crease are substantially known, respectively blind or continuous and through or segmented.

The continuous crease provides a compression, substantially at points, on the thickness of the material along an ideal folding line of the sheet, while the segmented crease provides to make an alternation of cut segments, or notches, through along the fold line, and of blind segments.

The choice of one or the other type of folding depends on the specifics of the material, on the fold or other. It is known that for the execution of a continuous crease a disk tool is used having a perimeter edge shaped transversely in a "V" or a "U", which is kept under pressure on a surface of the material, in order to deform it on the thickness and give the transverse "V" or "U" shaping to the crease. Normally the disk tool is disposed so as to make the crease in a direction parallel to the direction of feed of the strip or sheet of material with respect to the creasing unit.

It is also known to provide a plurality of disk tools parallel and distanced with respect to each other as desired along a transverse and/or longitudinal line, to the direction of feed of the strip or sheet of material, to make an equal number of creases, substantially parallel, on the sheet itself.

On the other hand, the segmented crease is typically made by means of punching, so as to make all the through notches provided on the sheet at the same time. By means of punching, the material is incised under pressure so as to make the notches and, above all with the thicker sheets, the possibilities are greater that some notches stay blind, or that flashes or curls of material are formed, as the punches come out from the notches just made. Therefore, the quality of the finished product is not always satisfactory.

Moreover, in the processing of sheets in which both continuous and segmented creases are provided, it is necessary to provide different and distinct processing stations in the same creasing unit, as well as complex and burdensome equipping steps of the production plant.

Therefore the plant often has to undergo long periods of inactivity, reducing the potential productivity. Cutting disks are also known which are alternatively brought into operative position on the sheet, with respect to the creasing disks.

This known solution is, however, very costly and complex and does not guarantee satisfactory results, above all for segmented creases with close pitch.

One purpose of the present invention is to produce a creasing tool which is both simple and economical to make and which allows to carry out both continuous creases and segmented creases, with reduced equipping times.

Another purpose of the present invention is to produce a tool which allows to make a continuous crease and segmented crease, guaranteeing a satisfactory quality of the finished product, even in the case of folding a relatively thick, or thick, sheet or strip.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea. In accordance with said purposes, a tool according to the present invention is used to make one or more creases on a sheet, or strip, made of a relatively rigid material, such as for example cardboard, plastic or materials with similar characteristics of rigidity, provided as a single sheet, a sheet of a continuous module, a portion of a strip. The tool according to the present invention is able to be selectively moved in relation to the sheet or strip, so as to define at least a first operative position, in which it is at a first level with respect to the sheet, and is able to make a continuous or blind crease, and a second operative position, in which it is at a second level with respect to the sheet, lower than the first level, and is able to make a through or segmented crease, or a true and proper cut.

The tool according to the present invention comprises at least a disk made of a rigid material, for example metal, provided around the circumference with at least a cutting segment able to make one or more notches on the thickness of the sheet or strip, so as to define the segmented or through crease, or able to make a cut proper.

According to the present invention, the tool comprises at least a crown made of an elastically deformable material, such as rubber or other elastomer, normally disposed covering at least the cutting segment of the disk, able to make the continuous or blind crease. The crown has a level of hardness such that, at a first working pressure, it resists deformation and makes a blind crease on the thickness of the sheet or strip.

The crown is also shaped, with respect to the cutting segment, so as to be able - A -

to deform elastically in a substantially radial direction toward the inside of the disk, when it undergoes a second working pressure greater than said first pressure, so as to uncover the cutting segment and allow the latter to carry out the relative incision on the sheet or strip. In this way, with the same tool, it is possible to make both a blind crease and a segmented or through crease, or a cut proper.

According to the invention, the choice of using the tool to carry out one or the other of the two shapings depends on the working pressure of the tool itself with respect to the sheet or strip, so as to selectively cause, or not, the elastic deformation of the crown and therefore uncover the cutting segment, or keep it covered.

With the present invention it is therefore not necessary to provide separate disks and punches to make the two different creases, which gives advantages in terms of the equipping times and costs, as well as the productivity of the machine or the plant in which the tool according to the present invention is used.

Moreover, the crown, being made of an elastically deformable material, can be made by casting so as to be able to obtain, in a simple and economical way, substantially any conformation of external shaping. It is therefore possible to obtain creases of a different shape with respect to traditional ones, improving the subsequent folding conditions of the sheet or strip.

The Applicant has verified that the creasing action made by the crown made of elastically deformable material on the sheet or strip determines a substantially wider crease impression than traditional creases, facilitating the precise folding of the sheet or strip even in the case where the latter is relatively thick. According to a variant, the disk provides a plurality of cutting segments angularly offset with respect to each other, to make, as a consequence of the rotation of the disk on the sheet or strip, a through crease with alternate segments.

According to another variant, the crown is disposed to cover at least one lateral flank and an external circular top of each cutting segment. According to this variant, when the tool acts at the second working pressure, the crown deforms elastically, sliding on the flank of the cutting segment and freeing the circular top toward the outside of the disk.

According to a further variant, the crown comprises two annular parts, each of which is disposed to cover a relative opposite lateral flank of the cutting segment and, usually, to cover the circular top.

According to this variant, when the tool acts at the second working pressure, the crown deforms elastically so that the two annular parts open centrally, each sliding on the respective flank of the cutting segment, freeing the circular top toward the outside.

In a condition of rotation of the disk, in which the second working pressure is applied, the annular parts press progressively on the sheet or strip, tending to open progressively, depending on their angular position with respect to the relatively rigid material.

Therefore the pressure on the annular parts increases progressively, initially defining a compression on the sheet or strip, and then they open progressively to allow the top of the cutting segment to exit radially with respect to the crown and to carry out the processing, segmented crease or through crease, or cut, on the thickness of the sheet or strip.

In this dynamic situation of rotation and deformation of the crown, the prior compression made by the crown not yet completely deformed, allows to compact the fibers which define the thickness of the sheet or strip, thus improving the processing conditions and the penetration of the cutting segments, avoiding the formation of flashes and substantially ensuring the complete through incision of all the notches. This is particularly advantageous in operations of through creases.

According to another variant, the tool comprises a rotary body on which two disks are circularly assembled substantially parallel and coaxial with respect to each other. They are spaced at a determinate pitch so as to make two parallel creases on the sheet or strip at the same time.

In this variant, at least one of the two disks comprises a crown made of a deformable material associated, according to the invention, with the relative cutting segment. BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some preferential forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein: - Fig. 1 is a three-dimensional view of a creasing tool according to the present invention;

- Fig. 2 is an enlarged detail of fig.1;

- Fig. 3 is a cross section of the tool in fig. 1, in a first operative condition; - Fig. 4 is a cross section of a detail of the tool in fig. 1 in a second operative condition;

- Fig. 5 is a three-dimensional view of a second form of embodiment of a tool according to the present invention;

- Fig. 6 is an enlarged detail of fig. 5; - Fig. 7 is a cross section of the tool in fig. 5.

DETAILED DESCRIPTION OF SOME PREFERENTIAL FORMS OF

EMBODIMENT

With reference to the attached drawings, a tool 10 according to the present invention is used to make both a continuous crease 11a (fig. 3), and also a segmented crease l ib (fig. 4), on relatively rigid material, in this case a sheet of cardboard 11 ; it can be a single sheet, for example, a sheet of a continuous module but also a portion of a strip. Simple to give an example, the crease 1 Ia or

1 Ib, made on the sheet of cardboard 11 by the tool 10 is intended to promote the exact and linear folding of the cardboard 11 , as for example in the automatic making of a packing case.

In the form of embodiment shown in figs. 1-4, the tool 10 comprises a rotary body 12, keyed axially on a hub 13, which is, in its turn, motorized, to give the rotary body 12 a determinate angular working speed.

The rotary body 12 has an annular seating 14 around its circumference which develops radially toward the inside of the rotary body 12 and inside which a disk 15 made of a rigid material is housed.

The disk 15 is provided with a plurality of cutting segments 16 on its periphery angularly offset with respect to each other at a determinate pitch, separated by mating empty spaces 23. Each cutting segment 16 is made of metal and has a substantially "V" shaped cross section, so as to be able to penetrate into the thickness of the sheet of cardboard 11 and make an through incision on it.

Moreover, in the circular seating 14 of the rotary body 12 an elastically deformable crown 17 is housed, in this case made of rubber, and disposed so as to keep the cutting segments 16 of the disk 15 normally covered.

In this case, the crown 17 comprises two annular rims or portions 19 and 20, facing each other, each of which is disposed laterally to the disk 15, so as to normally cover a respective lateral flank 16a of the cutting segments 16.

Each annular rim 19 and 20 is also disposed so as to normally cover the external circular top 16b of the cutting segments 16.

Moreover, the annular rims 19 and 20 are externally shaped so as to define the desired conformation of the cross section of the continuous crease 11a. The material which makes up the rims 19 and 20 allows the latter to be made by casting, and can confer on them substantially any conformation whatsoever.

Advantageously, the external shaping of the rims 19 and 20 is such as to define a continuous crease 11a wider than continuous traditional creases.

In this way, the folding conditions are made easier, even in the case of cardboard sheets 11 that are relatively thick.

The elastically deformable material which makes up the crown 17 has a level of hardness comprised between about 45 and about 65 units on the Shore scale.

This range of hardness has shown itself to be optimal for the correct, precise and clean execution, without residual flashes or curls, both in the segmented crease and the continuous crease, on sheets made with the materials described above.

In this way, thanks to the selection of material with a hardness as described above, with a first working pressure of the tool 10 on a sheet of cardboard 11, for example comprised between about 250 kN/m 2 and about 400 kN/m 2 , equal to about 2.5 bar and about 4 bar, the two rims 19 and 20 are not elastically deformed, and keep the cutting segments 16 covered and inactive. The resulting pressure is, in fact, insufficient to cause any elastic deformation thereof.

In this condition (fig. 1), the two rims 19 and 20 make a continuous crease 11a on the cardboard sheet 11.

With a second working pressure of the tool on the cardboard sheet 11, a pressure higher than the first and for example comprised between about 400 kN/m 2 and about 600 kN/m 2 , equal to about 4 bar and about 6 bar, the two rims 19 and 20 tend to deform progressively on contact with the cardboard sheet 11.

The progressive deformation determines a radial sliding of the rims 19 and 20 along the sides of the cutting segment 16 of the disk 15, toward the center of the rotary body 12, opening laterally and freeing the external circular top 16b of the cutting segment 16 (fig. 2).

In this condition, the cutting segment 16 is free to penetrate into the thickness of the cardboard sheet 11, defining the desired through notch. The alternation, during the course of the rotation of the disk 15, of cutting segments 16 and empty spaces 23, determines the desired through crease.

In the form of embodiment shown in figs. 5-7 and indicated for convenience by the reference number 110, two disks 15 are assembled in the circular seating 14 of the rotary body 12 and disposed substantially parallel with respect to each other and concentric to the rotary body 12. The distance between the two disks 15 is defined and maintained by an annular spacer 21, which is interposed between them.

In this case, the disk 15, shown on the right in fig. 7, is associated with a rim 20 of the elastically deformable crown 17, while the disk 15, shown on the left, is partially covered by a metal edge 22 which extends radially in a single piece from the rotary body 12.

It is clear that modifications and/or additions of parts may be made to the tool 10, 110 as described heretofore, without departing from the field and scope of the present invention.

For example, it comes within the field of the present invention to provide that the disk 15 has a substantially continuous cutting segment 16, to make a constant cut, and not a segmented one, of the cardboard, for example, when making a packing case, to define the closing flaps. According to a variant, in the solution shown in fig. 5, both the disks are associated with relative crowns 17 in an elastically deformable material.

According to another variant, the variation in working pressure of the tool 10 with respect to the sheet 11 is managed and commanded by an electronic command unit which is programmed and programmable. According to another variant, the variation in working pressure of the tool 10 with respect to the sheet 11 is managed and commanded manually.

It also comes within the field of the present invention to provide that the cutting segments 16 are made in a single piece on the circumference of the rotary body 12.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of tool to make at least a crease on a relatively rigid material, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.